A storage volume is the basic unit of storage, such as allocated space on a disk or a single tape cartridge. A storage pool is a collection of storage volumes. The server uses the storage volumes to store backed-up, archived, or space-managed files. The group of storage pools that you set up for the TSM server to use is called server storage. Storage pools can be arranged in a storage hierarchy.
The server has two types of storage pools that serve different purposes: primary storage pools and copy storage pools.
When a client node backs up, archives, or migrates data, the data is stored in a primary storage pool. The specific storage pool is identified as the destination in the management class associated with the data.
When a user tries to restore, retrieve, recall, or export file data, the requested file is obtained from a primary storage pool if possible. Primary storage pool volumes are always located onsite.
A primary storage pool can use random access storage (DISK device class) or sequential access storage (for example, tape or FILE device classes).
The server has a default DISKPOOL storage pool that uses random access disk storage. You can easily create other disk storage pools and storage pools that use tape and other sequential access media by using Device Configuration in the TSM Server Utilities.
The server does not require separate storage pools for archived, backed-up, or space-managed files. However, you may want to have a separate storage pool for space-managed files. Clients are likely to require fast access to their space-managed files. Therefore, you may want to have those files stored in a separate storage pool that uses your fastest disk storage.
When an administrator backs up a primary storage pool, the data is stored in a copy storage pool. See Backing Up Storage Pools for details.
A copy storage pool can use only sequential access storage (for example, a tape device class or FILE device class).
The copy storage pool provides a means of recovering from disasters or media failures. For example, when a client attempts to retrieve a file and the server detects an error in the file copy in the primary storage pool, the server marks the file as damaged. At the next attempt to access the file, the server obtains the file from a copy storage pool. For details, see Restoring Storage Pools, Using Copy Storage Pools to Improve Data Availability, Recovering a Lost or Damaged Storage Pool Volume, and Maintaining the Integrity of Files.
You can move copy storage pool volumes offsite and still have the server track the volumes. Moving copy storage pool volumes offsite provides a means of recovering from an onsite disaster.
Figure 14 shows one way to set up server storage. In this example, the storage defined for the server includes:
Policies defined in management classes direct the server to store files from clients in the ARCHIVE, BACKUP, or HSM disk storage pools. For each of the three disk storage pools, the tape primary storage pool is next in the hierarchy. As the disk storage pools fill, the server migrates files to tape to make room for new files. Large files may go directly to tape. For more information about setting up a storage hierarchy, see Overview: The Storage Pool Hierarchy.
You can back up all four of the primary storage pools to the one copy storage pool. For more information on backing up primary storage pools, see Backing Up Storage Pools.
Figure 14. Example of Server Storage
To set up this server storage hierarchy, do the following:
Use Volume Configuration in the TSM Server Utilities to add to disk storage. See Configuring Random Access Volumes on Disk Devices.
For most purposes, you should be able to use the Device Configuration utility to define storage pools. If you decide to set some parameters not handled by the utility or later change the storage pools, you can use either commands or the administrative Web interface.
This section provides a summary of parameters you can set and change for
storage pools using the administrative command-line or the administrative Web
interface. The section also provides examples of defining and updating
storage pools.
Task | Required Privilege Class |
---|---|
Define storage pools | System |
Update storage pools | System or unrestricted storage |
When you define a primary storage pool, be prepared to provide some or all
of the information that is shown in Table 12. Most of the information is optional. Some
information applies only to random access storage pools or only to sequential
access storage pools. Required parameters are marked.
Table 12. Information for Defining a Storage Pool
Information | Explanation | Type of Storage Pool |
---|---|---|
Storage pool name
(Required) | The name of the storage pool. | random, sequential |
Device class
(Required) | The name of the device class assigned for the storage pool. | random, sequential |
Pool type | The type of storage pool (primary or copy). The default is to define a primary storage pool. Once you define a storage pool, you cannot change whether it is a primary or a copy storage pool. | random, sequential |
Maximum number of scratch volumes
(Required for sequential access) | When you specify a value greater than zero, the server dynamically
acquires scratch volumes when needed, up to this maximum number.
For automated libraries, set this value equal to the physical capacity of the library. See Adding Scratch Volumes to an Automated Library Device. | sequential |
Access mode | Defines access to volumes in the storage pool for user operations (such
as backup and restore) and system operations (such as reclamation and server
migration). Possible values are:
| random, sequential |
Maximum file size | To exclude large files from a storage pool, set a maximum file
size. The maximum file size applies to the size of a physical file (a
single client file or an aggregate of client files).
Do not set a maximum file size for the last storage pool in the hierarchy unless you want to exclude very large files from being stored in server storage. | random, sequential |
Name of the next storage pool | Specifies the name of the next storage pool in the storage pool hierarchy, where files can be migrated or stored. See Overview: The Storage Pool Hierarchy. | random, sequential |
Migration thresholds | Specifies a percentage of storage pool occupancy at which the server begins migrating files to the next storage pool (high threshold) and the percentage when migration stops (low threshold). See Migration of Files in a Storage Pool Hierarchy. | random, sequential |
Migration processes | Specifies the number of processes that are used for migrating files from this storage pool. See Migration for Disk Storage Pools. | random |
Migration delay | Specifies whether migration of files should be delayed for a minimum number of days. See Keeping Files in a Storage Pool and How Tivoli Storage Manager Migrates Data from Sequential Access Storage Pools. | random, sequential |
Continue migration process | Specifies whether migration of files should continue even if files do not meet the requirement for migration delay. This setting is used only when the storage pool cannot go below the low migration threshold without moving additional files. See Keeping Files in a Storage Pool and How Tivoli Storage Manager Migrates Data from Sequential Access Storage Pools. | random, sequential |
Cache | Enables or disables cache. When cache is enabled, copies of files migrated by the server to the next storage pool are left on disk after the migration. In this way, a retrieval request can be satisfied quickly. See Using Cache on Disk Storage Pools. | random |
Collocation | With collocation enabled, the server attempts to keep all files belonging to a client node or a client file space on a minimal number of sequential access storage volumes. See Keeping a Client's Files Together: Collocation. | sequential |
Reclamation threshold | Specifies what percentage of reclaimable space can accumulate on a volume before the server initiates a space reclamation process for the volume. See Choosing a Reclamation Threshold. | sequential |
Reclamation storage pool | Specifies the name of the storage pool to be used for storing data from volumes being reclaimed in this storage pool. Use for storage pools whose device class only has one drive or mount point. See Reclaiming Volumes in a Storage Pool with One Drive. | sequential |
Reuse delay period | Specifies the number of days that must elapse after all of the files have been deleted from a volume, before the volume can be rewritten or returned to the scratch pool. See Delaying Reuse of Sequential Access Volumes. | sequential |
Overflow location | Specifies the name of a location where volumes are stored when they are ejected from an automated library by the MOVE MEDIA command. Use for a storage pool that is associated with an automated library or an external library. See Returning Reclaimed Volumes to a Library. | sequential |
For this example, suppose you have determined that an engineering department requires a separate storage hierarchy. You want the department's backed-up files to go to a disk storage pool. When that pool fills, you want the files to migrate to a tape storage pool. You want the pools to have the following characteristics:
You can define the storage pools in a storage pool hierarchy from the top down or from the bottom up. Defining the hierarchy from the bottom up requires fewer steps. To define the hierarchy from the bottom up, perform the following steps:
define stgpool backtape tape description='tape storage pool for engineering backups' maxsize=nolimit collocate=yes maxscratch=100
define stgpool engback1 disk description='disk storage pool for engineering backups' maxsize=5m nextstgpool=backtape highmig=85 lowmig=40
Restrictions:
You can update storage pools to change the storage hierarchy and other characteristics.
For example, suppose you had already defined the ENGBACK1 disk storage pool according to the previous example. Now you have decided to increase the maximum size of a physical file that may be stored in the storage pool. Use the following command:
update stgpool engback1 maxsize=100m
Table 13 gives tips on how to accomplish some tasks that are
related to storage pools.
Table 13. Task Tips for Storage Pools
For this Goal | Do This | For More Information |
---|---|---|
Keep the data for a client on as few volumes as possible | Enable collocation for the storage pool | Keeping a Client's Files Together: Collocation |
Reduce the number of volume mounts needed to back up multiple clients | Disable collocation for the storage pool | Keeping a Client's Files Together: Collocation |
Specify how the server reuses tapes | Set a reclamation threshold for the storage pool
Optional: Identify a reclamation storage pool | Reclaiming Space in Sequential Access Storage Pools |
Move data from disk to tape automatically when needed | Set a migration threshold for the storage pool
Identify the next storage pool | Migration for Disk Storage Pools |
Move data from disk to tape automatically based on how frequently users access the data or how long the data has been in the storage pool | Set a migration threshold for the storage pool
Identify the next storage pool Set the migration delay period | Migration for Disk Storage Pools |
Back up your storage pools | Define a copy storage pool
Set up a backup schedule | Defining a Copy Storage Pool |
Have clients back up directly to a tape storage pool | Define a sequential access storage pool that uses a tape device class
Change the policy that the clients use, so that the backup copy group points to the tape storage pool as the destination. | Defining or Updating Primary Storage Pools |